1. Field of the Invention
The present invention relates to a disc device for reading and reproducing information recorded on a disc type recording medium.
2. Description of the Related Art
There is known a disc device for optically or magnetically reading and reproducing video and sound information recorded on a disc type recording medium (hereinafter referred to as “disc”). When the disc is scratched or defected, the disc device cannot normally read and reproduce the information from a corresponding portion of the disc.
As countermeasures for a reading error, in Japanese Unexamined Patent Publication No. 8-167250 and Japanese Unexamined Patent Publication No. 2002-150699, when a defective sector exists in the disc such as a magnetic optical disc or hard disc, an alternate sector that acts as an alternate destination of the defective sector is arranged in the same disc or in a different memory etc. When recording the information on the disc, the information to be recorded in the defective sector is recorded in the alternate sector. When reproducing the information from the disc, the information recorded in the alternate sector is recorded on a memory etc. of high access speed, and then the information is read from the memory to complement the information corresponding to the defective sector.
While, in Japanese Unexamined Patent Publication No. 10-341389, information same as the information recorded on the disc such as a magnetic optical disc is recorded in a backup region of a cassette tape, and the information recorded in the backup region is re-recorded on the disc when the information cannot be read from the disc. When a free space of the disc runs out, the information with low access frequency that matches conditions set in advance is deleted from the disc, the same information recorded in the backup region is moved to a record holding region of the same cassette tape, and different information is recorded in the free space formed on the disc. The conditions for deleting the information include a recorded date being old, there being no plan for use at the moment, and the like.
In the disc devices of aforementioned Japanese Unexamined Patent Publications, when the information recorded on the disc is not the information recorded with the disc device, if the damaged portion from which the information cannot be normally read exists in the disc, correct reproduction cannot be performed since the information for complementing the recorded information in the damaged portion is not held in the alternate sector or memory etc. Furthermore, when the free space runs out in the recording region of the disc or cassette tape for recording the complementary information, new useful complementary information cannot be recorded.